What controls whether the fan icon is displayed on C4 thermostat?

[EagleMoon]

This may sound like a trivial, unimportant question but does anyone know exactly what controls whether or not the C4 thermostat displays the fan icon?

I have radiant floor heat so no actual fans, but I'd like that icon to confirm whether the thermostat is calling for heat. Is that possible? It seems to depend on some kind of feedback from the system's fan because if I set the thermostat fan control to "Auto", it never comes on.

BTW, even better would be to know when that zone's valve was actually open since there's some delay between calling for heat and the valve opening to deliver it, but that's a more advanced question at this point. That is, the valve in a radiant floor system is analogous to the fan in a forced-air system.

[neeshu]

We have a heated floor and we have an icon that looks like a floor cut away view with tubes. When the heat is off, it shows blue and when it's on it shows red.

Are you actually using a C4 thermostat to control your floor or you just want to use the icon?

[EagleMoon]

I have several C4 thermostats controlling various zones. They work correctly. However, there was some discussion in months past about exactly at what point does the thermostat turn son and off without any definitive information. It occurred to me the other day that it would be nice if the fan icon in the thermostat display would indicate whether the thermostat had activated the heat relay.

Note that I'm talking about the physical thermostat's display, not an icon in a C4 GUI, though an icon as you describe for the GUI would be interesting and might accomplish the same thing, albeit not as conveniently.